I have been looking at various ICs to interface to the prop to control the flight to make it easier for me to fly these things. I never did master the RC Airplane I used to launch... You see, I never made a successful landing, but I sure mastered the art of building and repair

The Gyros and SMD085 are analog and require ADC. Can I and do I use the prop or place a cheap chip in between for the conversion ???· More investigation needed.

The other requirement is the interface between these sensors, the RC unit, and the motors. I think I will use a second prop here (you know I believe in multiple props so this should come as no surprise). I am thinking of whether to use existing ESC's or roll my own MosFet design. I rather like the flexibility of my own drivers using the prop to control them.

Currently I have a Tower Pro 2409GS-18T Outrunner and 25A BEC (ESC). I am not sure if this is up to the task yet. $19.95 from HobbyCity. I will require 4 of these. I also have a Spectrum DX6i RC unit.

I have been getting ready for my next project... Well one that has been on the backburner since I got involved with Z80 emulation. And no, I am not giving that up either

My brother has a quad copter. I think his design is using Atmel chips as microcontrollers. He doesn't write his own software, but uses something that was developed by others. I myself am not too interested in flight model construction, except for the programmatic side of it. It's just that I have a emulation problem that I find more fascinating, because it hides so well.

I wish you good luck with your project!

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He died at the console of hunger and thirst.
Next day he was buried. Face down, nine edge first.

To work out if you need an external ADC then you'll have to try and get an idea of your sampling frequency requirements and resolution. You can get pretty small multichannel ADCs in any case.

I noticed as well that the LY530AL has a digital output.

A friend of mine also really wants to build a quad or hexa-copter at some point, we were also wondering about scratch building the ESCs, there are plenty of designs out there and a single prop could probably control even six motors, decisions decisions.

pullmoll: I am not so interested in the building part, but I certainly detest having to continually fix it after every single flight. My plane ended up being almost indestructable, having used thin marine ply in the end. However, the last flight (years ago) it nose dived (don't know why it did that - perhaps I clipped the field lights) and squashed the nose cone and broke the piston in the process. Otherwise, the plane is intact :-(

Cluso, if you wanted to try fixed wing again then go electric and get an EPP foam model with a pusher prop, almost impossible to break. LiPoly cells mean wing loadings can be nice and low and flight speeds slow, much easier to fly. So called park flyers are ideal.

Graham: According to the docs, the gyros only output an analog voltage, not a digital output :-(

I have no doubt a prop can control up to 6 motors and take 6 chanel RC input as well. Then it would just be a matter of communicating serially, 115200 would be fine, to get the input data from a second prop interfaced to all the sensors. Another alternative is that one prop do all sensors and the RC, and the second prop just control the motors. Either way, it is a relatively simple job for the prop to control the motors.

The biggest job is to interpret the data and thereby decide the various motor speeds.

Comments and things I have learnt along the way:
There are helicopters that are inherently stable, usually the counterrotating ones. This one has no heading gyro (sorry about the video spinning round!) but there are ones with heading gyros.

The catch with all these is you need a very calm day as the max speed is a slow running pace (most winds where I live on the top of a hill are deceptively fast once you get over tree height).

Quad vs Hex vs Dual (Chinook) vs Mono. I'd be interested to brainstorm this. Say you took two chinooks and joined them together to make a quad - what extra weight could you now lose. One battery and halve the flight time? Some of the body?

Re heading - the gyro does that very well, so you could control it with a compass if you wanted.

Stability in 3 axes - yes.

So - Pressure. I think those modules are getting cheaper and have resolutions of a few metres. So that should be enough to say "go up or go down slowly"

And then you just have GPS - not sure how small they go.

There seems to be a tradeoff between stability vs forward speed. If you want fast forward speeds it behaves more like a broomstick on your hand. I have one tiny helicopeter (a proper 4 channel one) that also has a gyro and has two settings for the user - 'fast' and 'stable'. For a hex or quad copter you would need to define those parameters in software.

Mock ye not! If I was writing the code, it probably would be in C or Basic.

I think if Cluso was adding GPS he is thinking about Unmanned Aerial Vehicles. And then the big decision - do you put the the brains on the plane/helicopter, or do you have the brains on the ground? Advantages both ways, though 'brains on the ground' immediately implies a transmitter on the plane, and that adds weight, and if you can add a micro for the same or less weight, better to have smarts on board.

All things being equal, I'd probably go for the absolute smallest propeller chip and try to leave out as much as possible, especially other chips and plugs and sockets and sd cards and memory chips. Which probably leads me to either Spin, Propbasic or Catalina. CP/M is probably overkill.

If the platform is inherently stable (eg that big helicopter above, which I just bought, but there are more available) then the code might be as simple as ' take GPS setting, take off, go up 10 metres, turn North, go 10 metres, turn South, go 10 metres, check position with GPS re wind, turn to correct direction, go back to takeoff position, go down slowly'. Of course, that assumes the helicopter is able to handle the wind, which is one problem I haven't solved yet (only calm enough every two weeks or so).

Never mind the GPS navigation. I said "Fly by wire" i.e. your "Primary Flight Computer" or PFC as they call it on the Boeing 777. The first problem is to keep the thing stable in the air. This is going to require fast reactions and needs to be reliable. This rules out any remote "brains" by wireless link. Probably rules out doing it in CP/M as well[noparse]:)[/noparse]

Having said that, if I were starting from scratch I think I'd have the thing tethered with a wire link back to the PC. Develop all the control algorithms and parameter tweaking on the PC. Then port the finished code to Spin/PASm on the Prop. Well, apart from the low level sensor drivers that is.

Drac & Heater: You should really see what HexaKopter in Germany are doing... Forget the guys name but WOW! He is using GPS waypoints and turns the transmitter off. Cameras are all the go on the quadcopters

I might have guessed you guys would suggest CPM - haha

I have just updated the top post with a replacement pressure transducer which is $9 and I2C with Temperature as well. This is usually good enough to give approximate height control. Just as long as you remember, pressure oscillates twice daily on top of atmospheric changes. So everything is relative. I have a recorder display on my catamaran because if pressure drops suddenly a storm is brewing !!

GPS is now small and cheap with inbuilt antenna but it has to be correctly located. This can come a little later. The Gyros still require ADC so maybe a Freescale 8 pin job here???

Re "This is going to require fast reactions and needs to be reliable."

The new helicopter designs coming out have solved a lot of this. Even a gumby like me can fly a model helicopter (and I cannot fly a model plane). I read once the concept of "update time" (maybe it was called something else), which is the number of times you have to make an adjustment based on what you see the helicopter doing. I think there was a figure of many times a second.

Well with a counterrotating prop, a flybar and a gyro, the time constant is now about once every 10 seconds. You can take off, hover at about 1 metre (height is very stable), then experiment with each of the controls independently without worrying if the whole thing is going to crash. 10 second adjustments ought to be really easy for the prop.

But you are right - for debugging and testing, two way telemetry makes sense. A very thin wire still has weight. Hmm - the little Yishi transceivers I use weigh about the same as the video recorder. I'll be interested to see what the lifting capability is for that big helicopter when it arrives. It *might* just be able to lift a transceiver module, matchbox clusoblade and perhaps even a video recorder too. If not, leave out the video.

The transceivers could be made lighter by removing the brass connector for the antenna, and going for a bare length of wire of the right length (which is all that is inside the antenna anyway).

"The LY530AL single-axis yaw gyroscope provides a choice of analog or digital absolute angular-rate outputs. LY530AL has a full scale of ±300 °/s and is capable of measuring rates with a -3 dB bandwidth up to 88 Hz, for the analog output, and 1kHz of output data rate for the digital output. Measuring 5 x 5 x 1.5 mm, the 16-pin LGA device also has a power-down pin to maximize overall system efficiency ensuring very low power consumption."

Graham: Interesting. The LY530ALH does not have I2C or SPI but the LY530AL does. However, the LY530AL is older and is no longer being stocked by DigiKey although they have plenty available now. There seems to be no dual gyros (pitch & roll) with I2C or SPI. They certainly would be nicer.

I am always cautious about ST products - got badly burnt by them many years ago !!!

BTW: I have an EPP wing (a pusher). That is what the kit was for but never finished it.

Re "BTW: I have an EPP wing (a pusher). That is what the kit was for but never finished it."

I've been pondering the best plane design for people who can't fly (which includes poorly programmed microcontrollers). I think it needs to have a large surface area, and then it will fly slowly. Slow = less damage. And the propeller (spinny thing, not the chip) can't be at the front as the front is the bit that flies into the ground/trees/fenceposts etc. So - a pusher is good. And I think and EPP wing answers all those criteria. Strong, light, less bits to break.

I suspect you would get a longer flight time from winged aircraft compared with helicopters. You might even catch a thermal. Come to think of it, catching a thermal is something that needs to be detectable by the controller. Also the problem of an artificial horizon for flying in clouds. PIR detectors seem to work well. And or self stabilising designs, eg a wing with a dihedral.

Drac: This is why I think a stabilised QuadCopter would be great. It can hover off the ground slowly and you can set the prop chip to only allow small changes and keep close to the ground until you get the idea of flying As soon as you let go of the stick the copter hovers giving you time to think about what to do next.

There is a nintendo wii controller which is a 3.3V 3 axis gyro with I2C... and there is an object on Obex too.
The unit is extremely small.
You can get one anywhere, only trouble is the screws (tri wing type).

Dr_acula, Cluso, Flying wings are very good if you are sure to get the CG right. Better in some ways are models with polyhedral (wings go up at each end) they are very stable. Lots of wing area for the weight (low wing loading) reduces flight speed and really helps. Free flight sims are available and are great fun and really help.

Massimo, I just drill them [noparse]:)[/noparse], the wiiplus module has them as well, someone stripped one and posted to the forum.

I got inspired by the Propeller with Propellers thread recently and started down the path of trying to make my own quadrotor flyer (yeah mixed in with everything else I am doing). I was planning to wait until I had done a first flight to post anything, but since you started this thread, I figured I'd jump in here.

I got a bunch of stuff from HobbyCity.com (HobbyKing), and also have several things from Parallax (Prop Protoboard, 2 LISY300 gyros, H48C, compass, and·GPS). My frame is made from some aluminum parts I had for my Vex robots, and I have 2 LiPo 2650mAh batteries for the power. Currently the frame, motors, ESCs, batteries,·reciever, and wiring weighs about 2.8lb. I expect that to get up to around 3.5-4.0lbs when I have all the electronics mounted. I have done some crude "lift tests" were I had it tethered down with 4 shorts strings to keep it semi stable (and keep it from attacking me). It lifts up and pulls against the tethers at about 1/3rd or so throttle.

Attached are a few pictures of what I have so far. The frame diameter is about 24.5 inches, and the motor diameter is about 1 inch. The propeller blades go out an additional 3.25 inches beyond the frame so the total diameter is about 31 inches.

Edit to add:
My current plan for the·control board is to have the 7 channels from the reciever feed into the prop, and have it drive the 4 ESCs/motors. The two gyros will be mounted perpendicular to the board for pitch and roll, and the compass will be used for yaw/heading. I'll have the H48C set up to align two of it's axis with the gyros. I think 8 cogs is more than enough to read the sensors process the sensor data·and reciever input and drive the ECSs.
ONe thing I hadn't considered before was using a pressure sensor like you decribe.· I'll need to add that to my plans for later.

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Check out the Propeller Wiki·and contribute if you can.

May I suggest that your frame may be a problem with vibration and the sensors. I only read this last night from someone who had to change to aluminium tube from U tube because the vibration was upsetting the sensors. If I come across the website again I will post a link. I too was thinking about U channel and with all the holes it makes mounting so easy. Your motors mount so easy too.

I found hobbycity have some very good pricing. Those motors look much better than the usual ones because it looks as though the cables are terminated properly. Is the bolt on the underside for mounting? They are certainly cheap enough. The ESC may be the way to go initially although I would like to make my own at least later so the prop can control them. So $24 per motor/esc makes $100 for the motors. I found a 4000mAh 20C 3S1P LiPo for $20 at HobbyCity.

Re the triblade propellors. These look good so may I ask why you chose 3 blades? And why did you choose these motors? I have no experience with electric flying.

I have also been reading up on maybe using the wii mote and the addon to give 6DOF (3 axis accelerometer + 3 axis gyro) for $40 using I2C.

Cluso99:
I am worried that the frame I have now might not work out, but I wanted to try with what I had and change things as needed while I go. I was planning to mount the Prop Protoboard suspended on little rubber screw "thingies" I have that should help a little with vibrations. We'll see when I get farther along.

The motors are nice, but they don't come looking like that picture. You have to solder the terminals onto the wires yourself (it does come with them as well as a set for the ESC side), and it comes with a bunch of "fiddly bits" that supposedly work with different kinds of blades and you mount those onto the motor as needed. It didn't come with any documentation, but it wasn't hard to figure out. I chose the motor mostly based on price and the Kv rating. Jason Dory said he was using something in the 1000Kv range, and these were cheap and 1500Kv and "hacker" friendly so I figured I'd be able to make them work one way or another.

I chose the 3 blade propellers because Jason Dory switched to them and said he got longer flight times (they are light and provide good lift). He had more information on his blog (linked in that thread and on his youtube videos). One issue I have noticed in testing is that the propellers start to slip on the motor shaft when running it high throttle. Maybe using some of the other "fiddly bits" will help.

The batteries I am using are from HobbyCity also, 3 cell LiPo 2650hAh with 30C rating (they say 30-40C on the battery itself) and they were $20 bucks each. I chose the 30C rating because I wanted the option to run all 4 motors from one battery and since they pull 2-6A standard and 8A max each a 30C battery can handle that. My setup currently uses 2 batteries, one per 2 motors, so I could have gone with 15-20C batteries if I wanted. I didn't go super high on the mAh rating because I was worried it might get too heavy.

I have no experience with any of this stuff. [noparse]:)[/noparse] I am just jumping in and seeing what I can do (something I learned from a crazy Giant Robot builder in Vermont).

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Check out the Propeller Wiki·and contribute if you can.

Roy: Thanks for the info. The battery info makes sense. I don't think my batteries will do the job so I will need new ones. The motor/esc I have (only 1 set) was what was recommended for my EPP Wing. It's not important to use them.

The 3 blade sounds good, but I don't think the prop savers can be used with them. Perhaps to stop them slipping the centre faces of the props need a rub with coarse sandpaper and the same with the metal facing thingo. Last thing we want is for them to slip while flying.

I saw another method of building the frame using aluminium tube and a 4-way plastic pipe joiner at the center. However, the engine mounting was more complex than rectangular tubing.

My plane parts are interstate on the boat so I will bring them down next week so I can drive the motor & esc with the prop. I am spending more time on land at the moment.

So that's what those things are called, eh? Prop Savers... I will have to try some of the other prop mounting hardware.

I figure I'll go through a couple different frame designs over time. This one will get me started, and I'll learn why it doesn't work or maybe figure out how to make it work. [noparse]:)[/noparse] I don't mind failing sometimes, you learn a lot doing that...

One nice thing about using an ESC is that it has built in protection for the batteries (avoiding killing you LiPo from over draining) and they have BEC (filtered 5v 2a power which normally is used for the reciever and such) which I should be able to use to power my control board. You control them just like a servo. Not sure what more control you would want/get by doing your own thing?

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Check out the Propeller Wiki·and contribute if you can.

The ESC are somewhat programable and I presume this is for setting the speed limitations and the maximum current, etc. So I thought it would be good to control it all in a cog for each motor. I guess I am trying to get the prop to do more so I have total control. Maybe too ambitious for now.

The programming of the speed control normally relates to the movement of the stick in a normal RC system, some will provide a different range of pulse lengths than others so occasionally people don't even get full throttle. Also you can sometimes set up other things like an electronic break, used to make sure folding propellers actually fold. Nothing to do with speed of current limits as there are none.

The battery protection they provide is not necessarily a good thing as the motors might just cut out, the battery will be saved but the aircraft turned in to a pile of parts. A better solution might be to have your own simple battery monitor and then implement a slow decent at a specific voltage level. To start with just landing when the performance drops is a good rule of thumb.

Someday I would also like to build a quad-copter. Seems to be popular lately. I don't need another project at the moment! I will see if I can dig up my notes from two years ago when I was doing research. I imagine there is a lot more data now.

Good luck on the project - I will be watching to see what I can learn from you guys.

These guys are doing great stuff with the Arduino, and I've been loitering on that site for months. Someone once said they're looking to implement the DCM (Direction Cosine Matrix) on the Propeller, but I've not seen anything since.

I too have purchased a load of motors, ESCs, and propellers from HobbyKing, but - as always - haven't yet got round to building anything. I'll be watching your progress with interest. (BTW: I'm planning on using a Sparkfun 5DOF unit, as that's what Jason Wood wrote a Kalman Filter object for [noparse];)[/noparse]